OSTEOPOROTIC FRACTURES DURING BISPHOSPHONATE DRUG HOLIDAY

Bisphosphonate (BP) drug holidays are recommended to lower the risk of rare adverse events, such as atypical femoral fractures and osteonecrosis of the jaw. However, there are minimal data on the optimal duration of these holidays. Our aim was to determine the clinical and laboratory parameters associated with increased fracture risk in patients on BP drug holiday.

A retrospective chart review was conducted of 401 patients with osteopenia or osteoporosis who began a BP drug holiday from 2004 to 2013. Collected parameters included demographics, prior therapy, bone mineral density (BMD), bone turnover markers, parathyroid hormone, calcium & vitamin D status, and clinical reports of fractures.

Sixty-two (15.4%) patients developed a fracture during follow-up. The yearly incidence of fractures ranged from 3.7 to 9.9%, peaking at 9.9% and 9.8% during years 4 and 5, respectively. The mean age of the fracture group was higher than the nonfracture group, though not significantly different (69.24 ± 12.26 years vs. 66.42 ± 10.18 years; P = .09). Compared to the nonfracture group, the fracture group had lower femoral neck BMD (0.75 ± 0.12 g/cm² vs. 0.79 ± 0.10 g/cm²; P = .03) and T-scores (-2.13 ± 0.99 vs. -1.78 ± 0.79; P = .01) at baseline.

Patients who begin BP drug holidays at high risk of fracture based on BMD, age, or other clinical risk factors warrant close follow-up, especially as its duration lengthens. Fracture risk analysis needs to be regularly assessed during the drug holiday and treatment resumed accordingly.

25-OHD = 25-hydroxyvitamin D AACE = American Association of Clinical Endocrinologists ACE = American College of Endocrinology BMD = bone mineral density BP = bisphosphonate BSAP = bone-specific alkaline phosphatase BTM = bone turnover marker FN = femoral neck LS = lumbar spine PTH = parathyroid hormone.